- 26 Jun, 2015 40 commits
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Joe Perches authored
Using "git diff | ./scripts/checkpatch -" does not have an easy mechanism to see the files and lines actually modified. Add --showfile to see the file and line specified in the diff. When --showfile is used without --terse, the second line of each message output is redundant, so it is removed. Signed-off-by:
Joe Perches <joe@perches.com> Cc: Petr Mladek <pmladek@suse.cz> Cc: Andy Whitcroft <apw@canonical.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Joe Perches authored
Add optional colors to make seeing message types a bit easier. Add --color command line switch, default:on Error is RED, warning is YELLOW, check is GREEN. The message type, if shown, is BLUE. Signed-off-by:
Petr Mladek <pmladek@suse.cz> Cc: Andy Whitcroft <apw@canonical.com> Signed-off-by:
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Joe Perches authored
If there are multiple patches/files on the command line, use a prefix before the patch/file message output like: -------------- patch/filename -------------- to make the identifying which messages go with which file/patch a bit easier to parse. Move the perl version and false positive messages after all the files have been scanned so that they are emitted only once. Standardize the NOTE: <...> form to always emit a blank line before the NOTE and always use print << "EOM" style. Signed-off-by: -
Joe Perches authored
Many lines of code extend beyond the maximum line length. Some of these are possibly justified by use type. For instance: structure definitions where comments are added per member like: struct foo { type member; /* some long description */ And lines that don't fit the typical logging message style where a string constant is used like: SOME_MACRO(args, "Some long string"); Categorize these long line types so that checkpatch can use a command-line --ignore=<type> option to avoid emitting some long line warnings. One of the existing checkpatch exclusions allowed kernel-doc argument documentation to exceed 80 columns because old versions of kernel-doc required single line documentation. The requirement was removed in 2009 so remove that exclusion. Add documentation to make the test a bit clearer. Signed-off-by: -
Joe Perches authored
String detection where a source line with a string constant is converted can either have an X or a space. Some of the string detection regexes do not allow the space character, but there is a handy $String variable that does. Convert the remaining uses of string detection regexes to use the $String variable to reduce possible false negatives. Signed-off-by:
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Alex Dowad authored
checkpatch uses various cues in its input patches and files to discover the names of user-defined types and modifiers. It then uses that information when processing expressions to discover potential style issues. Unfortunately, in rare cases, this means that checkpatch may give different results if you run it on several input files in one execution, or one by one! The reason is that it may identify a type (or something that looks like a type) in one file, and then carry this information over when processing a different file. For example, drivers/staging/media/bcm2048/radio-bcm2048.c contains this line (in a macro): size value; and drivers/staging/media/davinci_vpfe/vpfe_video.c has this line: while (size * *nbuffers > vpfe_dev->video_limit) If checkpatch processes these 2 files in a single command like: ./scripts/checkpatch.pl -f $file1 $file2 the (spurious) "size" type detected in the first file will cause it to flag the second file for improper use of the pointer dereference operator. To fix this, store types and modifiers found in a file in separate arrays from built-in ones, and reset the arrays of types and modifiers found in files at the beginning of each new source file. Signed-off-by:
Alex Dowad <alexinbeijing@gmail.com> Signed-off-by:
Andy Whitcroft <apw@canonical.com> Signed-off-by:
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Joe Perches authored
Using declarations like u_int16_t in kernel code is not preferred. Suggest the kernel sized types instead of the c99 types when not in the uapi directory. Add a $typeC99Typedefs variable for the types to check and neaten the other typedef variables. Signed-off-by:
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Joe Perches authored
Linus sayeth: : Pretty much every single time people use this "if : (waitqueue_active())" model, it tends to be a bug, because it means : that there is zero serialization with people who are just about to go : to sleep. It's fundamentally racy against all the "wait_event()" loops : that carefully do memory barriers between testing conditions and going : to sleep, because the memory barriers now don't exist on the waking : side. : : So I'm making a new rule: if you use waitqueue_active(), I want an : explanation for why it's not racy with the waiter. A big comment about : the memory ordering, or about higher-level locks that are held by the : caller, or something. Signed-off-by:
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Michal Simek authored
Fix kernel-doc format validation to be able to use kernel-doc script for checking it. Signed-off-by:
Michal Simek <michal.simek@xilinx.com> Reviewed-by:
Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Signed-off-by:
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Rasmus Villemoes authored
This makes a very large function a little smaller. Signed-off-by:
Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by:
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Rasmus Villemoes authored
In one case, we eliminate a local variable; in the other a strlen() call and some .text. Signed-off-by:
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Rasmus Villemoes authored
There's no point in starting over when we meet a '/'. This also eliminates a stack variable and a little .text. Signed-off-by:
NeilBrown <neilb@suse.de> Signed-off-by:
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Rasmus Villemoes authored
This eliminates a little .text and avoids repeating the strchr call when we meet a '!' (which will happen at least once). Signed-off-by:
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Rasmus Villemoes authored
There's probably not many slashes in the name, but starting over when we see one feels wrong. Signed-off-by:
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Rasmus Villemoes authored
Part of the disassembly of do_blk_trace_setup: 231b: e8 00 00 00 00 callq 2320 <do_blk_trace_setup+0x50> 231c: R_X86_64_PC32 strlen+0xfffffffffffffffc 2320: eb 0a jmp 232c <do_blk_trace_setup+0x5c> 2322: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1) 2328: 48 83 c3 01 add $0x1,%rbx 232c: 48 39 d8 cmp %rbx,%rax 232f: 76 47 jbe 2378 <do_blk_trace_setup+0xa8> 2331: 41 80 3c 1c 2f cmpb $0x2f,(%r12,%rbx,1) 2336: 75 f0 jne 2328 <do_blk_trace_setup+0x58> 2338: 41 c6 04 1c 5f movb $0x5f,(%r12,%rbx,1) 233d: 4c 89 e7 mov %r12,%rdi 2340: e8 00 00 00 00 callq 2345 <do_blk_trace_setup+0x75> 2341: R_X86_64_PC32 strlen+0xfffffffffffffffc 2345: eb e1 jmp 2328 <do_blk_trace_setup+0x58> Yep, that's right: gcc isn't smart enough to realize that replacing '/' by '_' cannot change the strlen(), so we call it again and again (at least when a '/' is found). Even if gcc were that smart, this construction would still loop over the string twice, once for the initial strlen() call and then the open-coded loop. Let's simply use strreplace() instead. Signed-off-by:Steven Rostedt <rostedt@goodmis.org> Liked-by:
Jens Axboe <axboe@fb.com> Signed-off-by:
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Rasmus Villemoes authored
There's no point in starting over every time we see a ','... Signed-off-by:
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Rasmus Villemoes authored
Strings are sometimes sanitized by replacing a certain character (often '/') by another (often '!'). In a few places, this is done the same way Schlemiel the Painter would do it. Others are slightly smarter but still do multiple strchr() calls. Introduce strreplace() to do this using a single function call and a single pass over the string. One would expect the return value to be one of three things: void, s, or the number of replacements made. I chose the fourth, returning a pointer to the end of the string. This is more likely to be useful (for example allowing the caller to avoid a strlen call). Signed-off-by:
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Kirill A. Shutemov authored
Currently we use per-cpu array to hold pointers to preallocated nodes. Let's replace it with linked list. On x86_64 it saves 256 bytes in per-cpu ELF section which may translate into freeing up 2MB of memory for NR_CPUS==8192. [akpm@linux-foundation.org: fix comment, coding style] Signed-off-by:
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by:
Johannes Weiner <hannes@cmpxchg.org> Signed-off-by:
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Sudeep Holla authored
bitmap_print_to_pagebuf uses scnprintf to copy the cpumask/list to page buffer. It handles the newline and trailing null character explicitly. It's unnecessary and also partially duplicated as scnprintf already adds trailing null character. The newline can be passed through format string to scnprintf. This patch does that simplification. However theoretically there's one behavior difference: when the buffer is too small, the original code would still output '\n' at the end while the new code(with this patch) would just continue to print the formatted string. Since this function is dealing with only page buffers, it's highly unlikely to hit that corner case. This patch will help in auditing the users of bitmap_print_to_pagebuf to verify that the buffer passed is large enough and get rid of it completely by replacing them with direct scnprintf() [akpm@linux-foundation.org: tweak comment] Signed-off-by:
Sudeep Holla <sudeep.holla@arm.com> Suggested-by:
Pawel Moll <Pawel.Moll@arm.com> Cc: Tejun Heo <tj@kernel.org> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Signed-off-by:
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Daniel Wagner authored
In case the call side is not providing a swap function, we either use a 32 bit or a generic swap function. When swapping around pointers on 64 bit architectures falling back to use the generic swap function seems like an unnecessary waste. There at least 9 users ('sort' is of difficult to grep for) of sort() and all of them use the sort function without a customized swap function. Furthermore, they are all using pointers to swap around: arch/x86/kernel/e820.c:sanitize_e820_map() arch/x86/mm/extable.c:sort_extable() drivers/acpi/fan.c:acpi_fan_get_fps() fs/btrfs/super.c:btrfs_descending_sort_devices() fs/xfs/libxfs/xfs_dir2_block.c:xfs_dir2_sf_to_block() kernel/range.c:clean_sort_range() mm/memcontrol.c:__mem_cgroup_usage_register_event() sound/pci/hda/hda_auto_parser.c:snd_hda_parse_pin_defcfg() sound/pci/hda/hda_auto_parser.c:sort_pins_by_sequence() Obviously, we could improve the swap for other sizes as well but this is overkill at this point. A simple test shows sorting a 400 element array (try to stay in one page) with either with u32_swap() or u64_swap() show that the theory actually works. This test was done on a x86_64 (Intel Xeon E5-4610) machine. - swap_32: NumSamples = 100; Min = 48.00; Max = 49.00 Mean = 48.320000; Variance = 0.217600; SD = 0.466476; Median 48.000000 each * represents a count of 1 48.0000 - 48.1000 [ 68]: ******************************************************************** 48.1000 - 48.2000 [ 0]: 48.2000 - 48.3000 [ 0]: 48.3000 - 48.4000 [ 0]: 48.4000 - 48.5000 [ 0]: 48.5000 - 48.6000 [ 0]: 48.6000 - 48.7000 [ 0]: 48.7000 - 48.8000 [ 0]: 48.8000 - 48.9000 [ 0]: 48.9000 - 49.0000 [ 32]: ******************************** - swap_64: NumSamples = 100; Min = 44.00; Max = 63.00 Mean = 48.250000; Variance = 18.687500; SD = 4.322904; Median 47.000000 each * represents a count of 1 44.0000 - 45.9000 [ 15]: *************** 45.9000 - 47.8000 [ 37]: ************************************* 47.8000 - 49.7000 [ 39]: *************************************** 49.7000 - 51.6000 [ 0]: 51.6000 - 53.5000 [ 0]: 53.5000 - 55.4000 [ 0]: 55.4000 - 57.3000 [ 0]: 57.3000 - 59.2000 [ 1]: * 59.2000 - 61.1000 [ 3]: *** 61.1000 - 63.0000 [ 5]: ***** - swap_72: NumSamples = 100; Min = 53.00; Max = 71.00 Mean = 55.070000; Variance = 21.565100; SD = 4.643824; Median 53.000000 each * represents a count of 1 53.0000 - 54.8000 [ 73]: ************************************************************************* 54.8000 - 56.6000 [ 9]: ********* 56.6000 - 58.4000 [ 9]: ********* 58.4000 - 60.2000 [ 0]: 60.2000 - 62.0000 [ 0]: 62.0000 - 63.8000 [ 0]: 63.8000 - 65.6000 [ 0]: 65.6000 - 67.4000 [ 1]: * 67.4000 - 69.2000 [ 4]: **** 69.2000 - 71.0000 [ 4]: **** - test program: static int cmp_32(const void *a, const void *b) { u32 l = *(u32 *)a; u32 r = *(u32 *)b; if (l < r) return -1; if (l > r) return 1; return 0; } static int cmp_64(const void *a, const void *b) { u64 l = *(u64 *)a; u64 r = *(u64 *)b; if (l < r) return -1; if (l > r) return 1; return 0; } static int cmp_72(const void *a, const void *b) { u32 l = get_unaligned((u32 *) a); u32 r = get_unaligned((u32 *) b); if (l < r) return -1; if (l > r) return 1; return 0; } static void init_array32(void *array) { u32 *a = array; int i; a[0] = 3821; for (i = 1; i < ARRAY_ELEMENTS; i++) a[i] = next_pseudo_random32(a[i-1]); } static void init_array64(void *array) { u64 *a = array; int i; a[0] = 3821; for (i = 1; i < ARRAY_ELEMENTS; i++) a[i] = next_pseudo_random32(a[i-1]); } static void init_array72(void *array) { char *p; u32 v; int i; v = 3821; for (i = 0; i < ARRAY_ELEMENTS; i++) { p = (char *)array + (i * 9); put_unaligned(v, (u32*) p); v = next_pseudo_random32(v); } } static void sort_test(void (*init)(void *array), int (*cmp) (const void *, const void *), void *array, size_t size) { ktime_t start, stop; int i; for (i = 0; i < 10000; i++) { init(array); local_irq_disable(); start = ktime_get(); sort(array, ARRAY_ELEMENTS, size, cmp, NULL); stop = ktime_get(); local_irq_enable(); if (i > 10000 - 101) pr_info("%lld\n", ktime_to_us(ktime_sub(stop, start))); } } static void *create_array(size_t size) { void *array; array = kmalloc(ARRAY_ELEMENTS * size, GFP_KERNEL); if (!array) return NULL; return array; } static int perform_test(size_t size) { void *array; array = create_array(size); if (!array) return -ENOMEM; pr_info("test element size %d bytes\n", (int)size); switch (size) { case 4: sort_test(init_array32, cmp_32, array, size); break; case 8: sort_test(init_array64, cmp_64, array, size); break; case 9: sort_test(init_array72, cmp_72, array, size); break; } kfree(array); return 0; } static int __init sort_tests_init(void) { int err; err = perform_test(sizeof(u32)); if (err) return err; err = perform_test(sizeof(u64)); if (err) return err; err = perform_test(sizeof(u64)+1); if (err) return err; return 0; } static void __exit sort_tests_exit(void) { } module_init(sort_tests_init); module_exit(sort_tests_exit); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR("Daniel Wagner"); MODULE_DESCRIPTION("sort perfomance tests"); Signed-off-by:Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by:
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Geert Uytterhoeven authored
The test data arrays, containing pointers to test strings, are never modified, so they can be const, too. Hence mark them "const" and "__initconst". This moves 28 pointers from ".init.data" to ".init.rodata". Signed-off-by:
Geert Uytterhoeven <geert@linux-m68k.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by:
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Chris Metcalf authored
bitmap_parselist("", &mask, nmaskbits) will erroneously set bit zero in the mask. The same bug is visible in cpumask_parselist() since it is layered on top of the bitmask code, e.g. if you boot with "isolcpus=", you will actually end up with cpu zero isolated. The bug was introduced in commit 4b060420 ("bitmap, irq: add smp_affinity_list interface to /proc/irq") when bitmap_parselist() was generalized to support userspace as well as kernelspace. Fixes: 4b060420 ("bitmap, irq: add smp_affinity_list interface to /proc/irq") Signed-off-by:Chris Metcalf <cmetcalf@ezchip.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by:
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Andrew Morton authored
Reported-by:
Rob Landley <rob@landley.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by:
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Joe Perches authored
This makes it easier to copy/paste names with periods to email clients. All the other names with commas already have quotation marks. Signed-off-by:
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Joe Perches authored
This makes it easier to copy/paste names with periods to email clients. All the other names with periods already have quotation marks. Signed-off-by:
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Jim Davis authored
Fix a few inconsistent annotations to show that the alsa-devel mailing list is moderated for non-subscribers. Signed-off-by:
Jim Davis <jim.epost@gmail.com> Cc: Joe Perches <joe@perches.com> Cc: Takashi Iwai <tiwai@suse.de> Signed-off-by:
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Joe Perches authored
Perl 5.22 emits a deprecated message when "\C" is used in a regex. Perl 5.24 will disallow it altogether. Fix it by using [A-Z] instead of \C. Signed-off-by:
Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by:
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Joe Perches authored
Section headers can be quite long and some are very long and duplicated for many initial characters. The current maximum length emitted for a section header is 20 bytes (or 17 bytes then ... when the section header length is > 20). Change that length to 50 so more of the section is shown. Example new output: $ ./scripts/get_maintainer.pl -f drivers/net/ethernet/broadcom/bnx2x/ Ariel Elior <ariel.elior@qlogic.com> (supporter:BROADCOM BNX2X 10 GIGABIT ETHERNET DRIVER) netdev@vger.kernel.org (open list:BROADCOM BNX2X 10 GIGABIT ETHERNET DRIVER) linux-kernel@vger.kernel.org (open list) Old: $ ./scripts/get_maintainer.pl -f drivers/net/ethernet/broadcom/bnx2x/ Ariel Elior <ariel.elior@qlogic.com> (supporter:BROADCOM BNX2X 10...) netdev@vger.kernel.org (open list:BROADCOM BNX2X 10...) linux-kernel@vger.kernel.org (open list) Signed-off-by:
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Joe Perches authored
Some people prefer not to be cc'd on patches. Add an ability to have a file (.get_maintainer.ignore) with names and email addresses that are excluded from being listed except when specifically listed as a maintainer in a section. Signed-off-by:
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Vasily Averin authored
Patch fixes drawbacks in heck_syslog_permissions() noticed by AKPM: "from_file handling makes me cry. That's not a boolean - it's an enumerated value with two values currently defined. But the code in check_syslog_permissions() treats it as a boolean and also hardwires the knowledge that SYSLOG_FROM_PROC == 1 (or == `true`). And the name is wrong: it should be called from_proc to match SYSLOG_FROM_PROC." Signed-off-by:
Vasily Averin <vvs@virtuozzo.com> Cc: Kees Cook <keescook@chromium.org> Cc: Josh Boyer <jwboyer@redhat.com> Cc: Eric Paris <eparis@redhat.com> Signed-off-by:
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Vasily Averin authored
The final version of commit 637241a9 ("kmsg: honor dmesg_restrict sysctl on /dev/kmsg") lost few hooks, as result security_syslog() are processed incorrectly: - open of /dev/kmsg checks syslog access permissions by using check_syslog_permissions() where security_syslog() is not called if dmesg_restrict is set. - syslog syscall and /proc/kmsg calls do_syslog() where security_syslog can be executed twice (inside check_syslog_permissions() and then directly in do_syslog()) With this patch security_syslog() is called once only in all syslog-related operations regardless of dmesg_restrict value. Fixes: 637241a9 ("kmsg: honor dmesg_restrict sysctl on /dev/kmsg") Signed-off-by:
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Tejun Heo authored
printk logbuf keeps various metadata and optional key=value dictionary for structured messages, both of which are stripped when messages are handed to regular console drivers. It can be useful to have this metadata and dictionary available to netconsole consumers. This obviously makes logging via netconsole more complete and the sequence number in particular is useful in environments where messages may be lost or reordered in transit - e.g. when netconsole is used to collect messages in a large cluster where packets may have to travel congested hops to reach the aggregator. The lost and reordered messages can easily be identified and handled accordingly using the sequence numbers. printk recently added extended console support which can be selected by setting CON_EXTENDED flag. From console driver side, not much changes. The only difference is that the text passed to the write callback is formatted the same way as /dev/kmsg. This patch implements extended console support for netconsole which can be enabled by either prepending "+" to a netconsole boot param entry or echoing 1 to "extended" file in configfs. When enabled, netconsole transmits extended log messages with headers identical to /dev/kmsg output. There's one complication due to message fragments. netconsole limits the maximum message size to 1k and messages longer than that are split into multiple fragments. As all extended console messages should carry matching headers and be uniquely identifiable, each extended message fragment carries full copy of the metadata and an extra header field to identify the specific fragment. The optional header is of the form "ncfrag=OFF/LEN" where OFF is the byte offset into the message body and LEN is the total length. To avoid unnecessarily making printk format extended messages, Extended netconsole is registered with printk when the first extended netconsole is configured. Signed-off-by:
Tejun Heo <tj@kernel.org> Cc: David Miller <davem@davemloft.net> Cc: Kay Sievers <kay@vrfy.org> Cc: Petr Mladek <pmladek@suse.cz> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by:
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Tejun Heo authored
Currently, each dynamic netconsole_target uses its own separate mutex to synchronize the configuration operations. This patch replaces the per-netconsole_target mutexes with a single mutex - dynamic_netconsole_mutex. The reduced granularity doesn't hurt anything, the code is minutely simpler and this'd allow adding operations which should be synchronized across all dynamic netconsoles. Signed-off-by:
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Tejun Heo authored
netconsole uses both bool and int for boolean values. Let's convert nt->enabled to bool for consistency. Signed-off-by:
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Tejun Heo authored
write_msg() grabs target_list_lock and walks target_list invoking netpool_send_udp() on each target. Curiously, it protects each iteration with netconsole_target_get/put() even though it never releases target_list_lock which protects all the members. While this doesn't harm anything, it doesn't serve any purpose either. The items on the list can't go away while target_list_lock is held. Remove the unnecessary get/put pair. Signed-off-by:
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Tejun Heo authored
printk log_buf keeps various metadata for each message including its sequence number and timestamp. The metadata is currently available only through /dev/kmsg and stripped out before passed onto console drivers. We want this metadata to be available to console drivers too so that console consumers can get full information including the metadata and dictionary, which among other things can be used to detect whether messages got lost in transit. This patch implements support for extended console drivers. Consoles can indicate that they want extended messages by setting the new CON_EXTENDED flag and they'll be fed messages formatted the same way as /dev/kmsg. "<level>,<sequnum>,<timestamp>,<contflag>;<message text>\n" If extended consoles exist, in-kernel fragment assembly is disabled. This ensures that all messages emitted to consoles have full metadata including sequence number. The contflag carries enough information to reassemble the fragments from the reader side trivially. Note that this only affects /dev/kmsg. Regular console and /proc/kmsg outputs are not affected by this change. * Extended message formatting for console drivers is enabled iff there are registered extended consoles. * Comment describing /dev/kmsg message format updated to add missing contflag field and help distinguishing variable from verbatim terms. Signed-off-by:
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Tejun Heo authored
The extended message formatting used for /dev/kmsg will be used implement extended consoles. Factor out msg_print_ext_header() and msg_print_ext_body() from devkmsg_read(). This is pure restructuring. Signed-off-by:
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Tejun Heo authored
This patchset updates netconsole so that it can emit messages with the same header as used in /dev/kmsg which gives neconsole receiver full log information which enables things like structured logging and detection of lost messages. This patch (of 7): devkmsg_read() uses 8k buffer and assumes that the formatted output message won't overrun which seems safe given LOG_LINE_MAX, the current use of dict and the escaping method being used; however, we're planning to use devkmsg formatting wider and accounting for the buffer size properly isn't that complicated. This patch defines CONSOLE_EXT_LOG_MAX as 8192 and updates devkmsg_read() so that it limits output accordingly. Signed-off-by:
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Colin Ian King authored
The KERN_INFO prefix is being prepended to KERN_DEBUG when using the dprink macro, Remove it as it is extraneous since we are printing the message out as debug via dprintk(). Fixes smatch warning: drivers/misc/altera-stapl/altera.c:2454 altera_init() warn: KERN_* level not at start of string Signed-off-by:
Colin Ian King <colin.king@canonical.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Igor M. Liplianin <liplianin@netup.ru> Cc: Mauro Carvalho Chehab <mchehab@infradead.org> Signed-off-by:
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Josh Triplett authored
clone has some of the quirkiest syscall handling in the kernel, with a pile of special cases, historical curiosities, and architecture-specific calling conventions. In particular, clone with CLONE_SETTLS accepts a parameter "tls" that the C entry point completely ignores and some assembly entry points overwrite; instead, the low-level arch-specific code pulls the tls parameter out of the arch-specific register captured as part of pt_regs on entry to the kernel. That's a massive hack, and it makes the arch-specific code only work when called via the specific existing syscall entry points; because of this hack, any new clone-like system call would have to accept an identical tls argument in exactly the same arch-specific position, rather than providing a unified system call entry point across architectures. The first patch allows architectures to handle the tls argument via normal C parameter passing, if they opt in by selecting HAVE_COPY_THREAD_TLS. The second patch makes 32-bit and 64-bit x86 opt into this. These two patches came out of the clone4 series, which isn't ready for this merge window, but these first two cleanup patches were entirely uncontroversial and have acks. I'd like to go ahead and submit these two so that other architectures can begin building on top of this and opting into HAVE_COPY_THREAD_TLS. However, I'm also happy to wait and send these through the next merge window (along with v3 of clone4) if anyone would prefer that. This patch (of 2): clone with CLONE_SETTLS accepts an argument to set the thread-local storage area for the new thread. sys_clone declares an int argument tls_val in the appropriate point in the argument list (based on the various CLONE_BACKWARDS variants), but doesn't actually use or pass along that argument. Instead, sys_clone calls do_fork, which calls copy_process, which calls the arch-specific copy_thread, and copy_thread pulls the corresponding syscall argument out of the pt_regs captured at kernel entry (knowing what argument of clone that architecture passes tls in). Apart from being awful and inscrutable, that also only works because only one code path into copy_thread can pass the CLONE_SETTLS flag, and that code path comes from sys_clone with its architecture-specific argument-passing order. This prevents introducing a new version of the clone system call without propagating the same architecture-specific position of the tls argument. However, there's no reason to pull the argument out of pt_regs when sys_clone could just pass it down via C function call arguments. Introduce a new CONFIG_HAVE_COPY_THREAD_TLS for architectures to opt into, and a new copy_thread_tls that accepts the tls parameter as an additional unsigned long (syscall-argument-sized) argument. Change sys_clone's tls argument to an unsigned long (which does not change the ABI), and pass that down to copy_thread_tls. Architectures that don't opt into copy_thread_tls will continue to ignore the C argument to sys_clone in favor of the pt_regs captured at kernel entry, and thus will be unable to introduce new versions of the clone syscall. Patch co-authored by Josh Triplett and Thiago Macieira. Signed-off-by:
Josh Triplett <josh@joshtriplett.org> Acked-by:
Andy Lutomirski <luto@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Thiago Macieira <thiago.macieira@intel.com> Signed-off-by:
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